This application relates to digital image and video processing.
Various applications exist for digital video communication and storage, and corresponding international standards have been and are continuing to be developed. To achieve low bit rate communications, MPEG-2, MPEG-4 Part 2, and H.263 standards divide a picture into 16×16 non-overlapping blocks called macro block and then use 2 dimensional (2D) order-8 discrete cosine transform (DCT) in digital video compression algorithms used in the coding standards. Recently, new video coding standards, such as H.264/AVC, AVS and SMPTE 421M etc, have been proposed that use 2D order-4 or order-8 transforms to provide a better compressibility than the video standards based on the 2D order-8 DCT. In those standards, the 2D order-4 or order-8 transforms are used so as to seek a trade-off between computational efficiency and coding efficiency.